The secretary of state has been the chief advocate of President Obama’s desire to launch a limited military strike against Syria. But in his efforts to sell the campaign, Kerry has given us at least three reasons to be circumspect.

The first was his reply to Sen. Robert Menendez, D-N.J., chairman of the Senate Foreign Relations Committee, about whether the administration would accept “a prohibition for having American boots on the ground.”

Kerry began by saying there was no intention to put boots on the ground, but added:

“But in the event Syria imploded, for instance, or in the event there was a threat of a chemical-weapons cache falling into the hands of al-Nusra (an al-Qaeda group), or someone else, and it was clearly in the interest of our allies and all of us, the British, the French, and others, to prevent those weapons of mass destruction falling into the hands of the worst elements, I don’t want to take off the table an option that might or might not be available to a president of the United States to secure our country.”

He attempted to retract this moment of candor by telling Menendez, “The bottom line is, the president has no intention and will not, and we do not want to, put American troops on the ground to fight this — or be involved in the fighting of this civil war, period.” When that answer was unsatisfactory to Sen. Bob Corker, R-Tenn., Kerry added:

“Well, let me be very clear now because I don’t want anything coming out of this hearing that leaves any door open to any possibility. So let’s shut that door now as tight as we can.”

Kerry was right the first time. The only thing certain about military action is its unpredictability, and should an American attack create chaos, we’d own the result. There are any number of calamitous scenarios that could result, not the least of which is that a U.S. attack on Syria could spark a war between Iran and Israel. The chief of Iran’s Revolutionary Guard said an attack on Syria would lead to the “destruction of Israel” and become a “second Vietnam” for America.

It’s a fair question to ask whether the United States is more or less safe if our attack on Syria causes Iran to strike Israel and Israel to retaliate against Iran. Optimistically, Syria would then be disciplined and dictators put on notice, while Israel stood tall and Iran had its nuclear program obliterated. Then again, maybe we’d touch off a wide-ranging conflict in which every country in the Mideast is choosing sides.

Next was Kerry’s interview with MSNBC’s Chris Hayes on the day the New York Times published a chilling photograph showing Syrian rebels executing seven of President Bashar al-Assad’s soldiers. When Hayes asked if the executioners would soon become our allies, Kerry responded:

“No. In fact, I believe that those men in those videos are disadvantaged by an American response to the chemical-weapons use because it, in fact, empowers the moderate opposition. We all know there are about 11 really bad opposition groups — so-called opposition. They’re not — they’re fighting Assad. They are not part of the opposition that is being supported by our friends and ourselves. That is a moderate opposition. They condemn what has happened today and they will — they are and we are busy separating the support we’re getting from any possibility of that support going to these guys.”

Wait a minute. There are 11 “really bad” opposition groups? And somehow our disciplining Assad is not going to give them a boost but will help more moderate opposition groups? That makes no sense. Any weakening of Assad could only be a boost to all of his opponents, including those supported by al-Qaeda.

Kerry should know that we can’t control the outcome of a civil war in a far-off land any more than we can rely on the election of our friends in fledgling democracies. Americans get that. Last week, 62 percent of those responding told CBS News/New York Times pollsters they opposed U.S. intervention in Syria. When asked whether the United States should intervene to turn dictatorships into democracies, 72 percent said no — the highest in a decade of polling on that question.

Americans have had enough of foreign entanglements in which our security is not directly threatened. And while we’re heartbroken about the human toll in Syria, we’re not quite sure why 1,000 deaths from chemical weapons necessitate our involvement but 99,000 deaths from conventional weapons didn’t warrant a response.

On Monday in London, Kerry tried to assuage concerns about a deepening involvement in Syria by saying our actions would be an “unbelievably small, limited” effort.

That should only heighten our concern. Why introduce such volatility in an already unstable and dangerous part of the world if our stated goal is only to skin Assad’s knee? Wasn’t the post-Vietnam lesson to not get involved unless we are prepared to win?

Kerry gave us three good reasons to be opposed, and I can think of three more close to me. Last week, each of them began a new school year.